Device for processing eye tissue by means of a pulsed laser beam

ABSTRACT

An ophthalmological device ( 1 ) for processing eye tissue includes a projection optical unit for focused projection of a laser beam (L) into the eye tissue, and a scanner system upstream of the projection optical unit for beam-deflecting scanning of the eye tissue with the laser beam (L) in a scanning movement (s&#39;) performed over a scanning angle along a scanning line(s). The ophthalmological device includes at least one optical element upstream of the projection optical unit, the optical element configured to generate a divergence—dependent on the scanning angle—of the laser beam (L), the scanning line(s) tilted in a plane running through the optical axis of the projection optical unit and the scanning line(s). Tilting of the scanning line(s)displaces—dependent on the scanning angle—the focus of the laser pulses projected into the eye tissue without vertical displacement of the projection optical unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims benefit of and priority to U.S.Provisional Patent Application Ser. No. 61/563,637, filed Nov. 25, 2011,entitled VORRICHTUNG ZUM BEARBEITEN VON AUGENGEWEBE MITTELS EINESGEPULSTEN LASERSTRAHLS, the entire contents of which are herebyincorporated by reference herein.

TECHNICAL FIELD

The present invention relates to an ophthalmological device forprocessing eye tissue by means of a pulsed laser beam. The presentinvention relates, in particular, to an ophthalmological devicecomprising a projection optical unit for the focused projection of thelaser beam into the eye tissue, and a scanner system disposed upstreamof the projection optical unit and serving for the beam-deflectingscanning of the eye tissue with the laser beam.

PRIOR ART

For processing eye tissue by means of a laser beam, a processing regionis scanned with laser pulses by the pulsed laser beam being deflected inone or two scanning directions by means of suitable scanner systems(deflection devices). The deflection of the light beams or of the laserpulses, for example femtosecond laser pulses, is generally performed bymeans of movable mirrors which are pivotable about one or two scanningaxes, for example by means of galvanoscanners, piezoscanners, polygonscanners or resonance scanners.

U.S. Pat. No. 7,621,637 describes a device for processing eye tissue,said device having a base station with a laser source for generatinglaser pulses and a scanner arranged in the base station with movabledeflection mirrors for deflecting the laser pulses in a scanningdirection. The deflected laser pulses are transmitted via an opticaltransmission system from the base station to an application head, whichmoves over a working region in accordance with a scanning pattern bymeans of a mechanically moved projection optical unit. The deflection inthe scanning direction, which is much faster compared with themechanical movement, is superimposed in the application head onto themechanical movement of the projection optical unit and thus onto thescanning pattern thereof. A fast scanner system in the base stationenables a fine movement of the laser pulses (microscan), which issuperimposed onto the scanning pattern of the movable projection opticalunit that covers a large processing region, for example the entire eye.

Although the known systems make it possible to process simple scanningpatterns, for example to cut a tissue flap, this generally beingperformed as a large area segment with a simple edge geometry, in thecase of applications which involve not only making tissue cuts in asubstantially horizontally oriented processing area on a common focalarea, but also intending to make cuts with a vertical cut component overdifferent focus heights, e.g. cuts that are vertical or run obliquelywith respect to the horizontal, the vertical movement of the projectionoptical unit or at least parts thereof for a vertical variation of thefocus and thus of the cut height proves to be too slow for making cutswith a vertical component, that is to say with a variable depth of focusduring cutting.

SUMMARY OF THE INVENTION

It is an object of the present invention to propose a device forprocessing eye tissue by means of a pulsed laser beam which does nothave at least some of the disadvantages of the prior art. In particular,it is an object of the present invention to propose a device forprocessing eye tissue by means of a pulsed laser beam focused by aprojection optical unit which enables tissue cuts with a vertical cutcomponent, without vertical displacements of the projection optical unithaving to be performed for this purpose.

According to the present invention, these aims are achieved by means ofthe features of the independent claims. Further advantageous embodimentsare additionally evident from the dependent claims and the description.

An ophthalmological device for processing eye tissue by means of apulsed laser beam comprises a projection optical unit for the focusedprojection of the laser beam or of the laser pulses into the eye tissue,and a scanner system disposed upstream of the projection optical unitand serving for the beam-deflecting scanning of the eye tissue with thelaser beam or the laser pulses in a scanning movement performed over ascanning angle along a scanning line.

The abovementioned aims are achieved by the present invention, inparticular, by virtue of the fact that at least one optical element isdisposed upstream of the projection optical unit, which optical elementis designed to generate a divergence of the laser beam, said divergencebeing dependent on the scanning angle. The divergence of the laser beam,which is varied by the optical element depending on the scanningmovement, corresponds to a modulation of the divergence of the laserbeam in a direction running perpendicular to the optical transmissionaxis. The at least one optical element comprises, for example, a wedgeplate, a prism, a lens, a diffractive optical element and/or anaspherical mirror. The at least one optical element is arranged in thebeam path from the scanner system to the projection optical unit. In oneembodiment variant, the at least one optical element is arranged in thescanner system.

Preferably, the at least one optical element is designed to generate thedivergence—dependent on the scanning angle—of the laser beam for adisplacement of the focused projection in the projection direction, saiddisplacement being dependent on the scanning angle.

Preferably, the at least one optical element is designed to generate thedivergence—dependent on the scanning angle—of the laser beam for adisplacement of the focused projection in the projection direction, saiddisplacement being dependent on the scanning angle.

Preferably, the at least one optical element is designed to generate thedivergence—dependent on the scanning angle—of the laser beam for atargeted tilting of the scanning line.

The tilting of the scanning line enables a displacement—dependent on thescanning angle—of the focus of the laser pulses projected into the eyetissue without vertical displacement of the projection optical unit orof individual components of the projection optical unit.

The at least one optical element is designed in particular to generatethe divergence—dependent on the scanning angle—of the laser beam for atilting of the scanning line with a defined tilting angle in a planedefined by the scanning line and an optical axis of the projectionoptical unit.

By virtue of a corresponding configuration, in particular dimensionalconfiguration, of the at least one optical element, in one variant adeformation of the scanning line is produced in a plane defined by thescanning line and the optical axis of the projection optical unit.

In one embodiment variant, the at least one optical element for settingthe divergence—dependent on the scanning angle—of the laser beam can beintroduced into the beam path and can be withdrawn from the beam path.

In a further embodiment variant, the at least one optical element forsetting the divergence—dependent on the scanning angle—of the laser beamis adjustable in the beam path. The at least one optical element isadjustable, for example, by a rotation about an optical axis, a rotationabout an axis parallel to the optical axis, a tilting about an axis ofrotation and/or a displacement along a translation axis tilted withrespect to the optical axis.

In one embodiment variant, the ophthalmological device comprises arotation element arranged in the beam path and serving for rotating ascanning plane defined by the scanning movement about an opticaltransmission axis, and the at least one optical element is disposedupstream of the rotation element in the beam path.

In a further embodiment variant, the ophthalmological device comprises afurther, second scanner system disposed downstream of the scanner systemand serving for scanning the eye tissue with the laser beam along aprocessing line, wherein the scanning movement of the upstream firstscanner system is superimposed on the processing line, and wherein theat least one optical element is designed to generate thedivergence—dependent on the scanning angle—of the laser beam for atargeted tilting of a cutting area defined by the scanning line and theprocessing line.

In one embodiment variant, the ophthalmological device comprises acontrol module, which is designed to adjust the at least one opticalelement in such a way that with the divergence—dependent on the scanningangle—of the laser beam the scanning line is tilted with a predefinedtilting angle. In the case of the variant with the downstream secondscanner system, the control module is designed to adjust the at leastone optical element in such a way that with the divergence—dependent onthe scanning angle—of the laser beam, the cutting area is tilted with apredefined tilting angle.

The control module is designed in particular to adjust the at least oneoptical element in such a way that with the divergence—dependent on thescanning angle—of the laser beam, the scanning line is tilted with thepredefined tilting angle in a plane defined by the scanning line and anoptical axis of the projection optical unit.

In a further embodiment variant, the control module is designed, duringthe processing of the eye tissue, to determine a changed tilting angleand to adjust the at least one optical element in such a way that thescanning line or the cutting area is tilted with the changed tiltingangle.

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the present invention is described below on the basisof an example. The example of the embodiment is illustrated by thefollowing enclosed figures:

FIG. 1: shows a block diagram schematically illustrating anophthalmological device for processing eye tissue with a pulsed laserbeam, which device comprises a scanner system for scanning the eyetissue along a scanning line and a tilting system for tilting thescanning line.

FIG. 1 a: shows a block diagram of the ophthalmological device in which,for the purpose of tilting the scanning line, at least one opticalelement is disposed upstream of the projection optical unit andgenerates in the beam path a laser beam divergence dependent on thescanning angle.

FIG. 1 b: shows a block diagram of the ophthalmological device in which,for the purpose of tilting the scanning line, a divergence modulator isdisposed upstream of the scanner system and dynamically changes thedivergence of the laser beam.

FIG. 1 c: shows a block diagram of an application head of theophthalmological device, in which application head the projectionoptical unit can be tilted about an axis of rotation for the purpose oftilting the scanning line.

FIG. 1 d: shows a block diagram illustrating the projection optical unitand correspondingly the scanning line in a tilted state.

FIG. 2 a: shows a schematic cross section through a portion of the beampath which illustrates the scanning movement of the laser beam by ascanning angle and the resultant movement of the focus of the laser beamalong the scanning line.

FIG. 2 b: shows the schematic cross section of the beam path portion inthe case of a variation of the divergence of the laser beam depending onthe scanning angle, and the resultant tilting of the scanning line by atilting angle.

FIG. 3: shows a schematic cross section of a portion of the beam path ina divergence modulator with at least one displaceable lens andillustrates the laser beam divergence varied by the displacement of thelens.

FIG. 4 a: shows in the plan view of the cornea, the superimposition ofthe scanning movement onto a processing line for processing the eyetissue in an extended processing region.

FIG. 4 b: shows, in the cross section of the cornea, the tilted scanningline along which the eye tissue is scanned and processed by the pulsedlaser beam.

FIG. 4 c: shows, in the cross section of the cornea, the tilted scanninglines of a plurality of processing paths along which the eye tissue isscanned and processed by the pulsed laser beam.

FIG. 5: shows, in the upper part in the plan view of the cornea, anexemplary application of a circle-arc-shaped conic path cut which, as isillustrated in the cross section of the cornea illustrated in the lowerpart, is based on a tilted scanning line that is moved along acircle-arc-shaped processing line.

FIG. 6: shows, in the upper part in the plan view of the cornea, anexemplary application of two circle-arc-shaped vertical cuts which, asis illustrated in the cross section of the cornea illustrated in thelower part, are in each case based on a tilted scanning line that ismoved along the relevant processing line, in a manner oriented in thedirection of a circle-arc-shaped processing line.

FIG. 7: shows, in the upper part in the plan view of the cornea, anexemplary application of a plurality of vertical cuts which are orientedtoward a common center and which, as is illustrated in the cross sectionof the cornea illustrated in the lower part, are in each case based on atilted scanning line that is moved along the relevant processing line,in a manner oriented in the direction of a processing line orientedtoward the center.

WAYS OF EMBODYING THE INVENTION

In FIGS. 1, 1 a and 1 b, the reference sign 1 in each case refers to anophthalmological device for processing eye tissue by means of laserpulses, for example the cornea 22 or other tissue of an eye 2.

As is illustrated schematically in FIGS. 1, 1 a and 1 b, theophthalmological device 1 comprises an optical transmission system 100for transmitting laser pulses of a pulsed laser beam L supplied by alaser source 18 to a projection optical unit 10. The projection opticalunit 10 is designed for the focused projection of the pulsed laser beamL or of the laser pulses for the punctiform tissue decomposition at afocus F (focal point) within the eye tissue. In FIGS. 1, 1 a, 1 b, 1 d,2 a and 2 b, the laser beam L projected by the projection optical unit10 is designated by the reference sign L*.

The laser source 18 comprises, in particular, a femtosecond laser forgenerating femtosecond laser pulses having pulse widths of typically 10fs to 1000 fs (1 fs=10⁻¹⁵ s). The laser source 18 is arranged in aseparate housing or in a housing jointly with the projection opticalunit 10.

It should be emphasized at this juncture that the reference sign Lgenerally designates the pulsed laser beam L or the laser pulses thereofin the beam path from the laser source 18 as far as the focus F, butthat depending on the context further reference signs are also used todesignate the pulsed laser beam L or the laser pulses thereof at aspecific location in the beam path or in the optical transmission system100.

As is illustrated in FIG. 1 c, the projection optical unit 10 isincorporated into an application head 3, for example, which can beplaced onto the eye 2. The application head 3 is preferably placed ontothe eye 2 via a contact body 31, which is light-transmissive at least inplaces, and fixed to the eye 2 by means of a vacuum-controlled suctionring 32, for example, wherein the contact body 31 and the suction ring32 are connected to the application head 3 fixedly or removably. In oneembodiment variant, the projection optical unit 10 comprises a focusingdevice 19 for setting the depth of focus, for example one or a pluralityof movable lenses or a drive for moving the entire projection opticalunit 10.

As can be seen in FIGS. 1, 1 a and 1 b, the ophthalmological device 1comprises at least one scanner system 14 disposed upstream of theprojection optical unit 10 and serving for scanning the eye tissue alonga scanning line s. The scanner system 14 is designed to deflect thepulsed laser beam L or the laser pulses in order to scan the eye tissuein a processing fashion. The scanner system 14 comprises one or aplurality of movable deflection mirrors, for example a rotating polygonmirror (polygon scanner), and enables beam-deflecting scanning of theeye tissue with the pulsed laser beam L in a scanning movement s′performed over a scanning angle β along a scanning line s, as isillustrated in FIG. 2 a. By means of the scanning movement s′, the focusF of the projected laser beam L* is moved along the scanning line s, forexample proceeding from the position of the focus F in the case of adeflection of the laser beam L with the scanning angle β₁ to theposition of the focus F′ in the case of a deflection of the laser beam Lwith the scanning angle β₂.

The beam-deflecting scanner system 14 is embodied as a resonant,oscillating, or freely addressable scanner depending on the operatingmode and/or construction and comprises, for example, a galvanoscanner, apiezo-driven scanner, an MEM (microelectro-mechanical scanner), an AOM(acousto-optical modulator) scanner or an EOM (electro-opticalmodulators) scanner.

As is illustrated in FIGS. 1 a and 1 b, in one embodiment variant theophthalmological device 1 comprises a rotation element 12, which isarranged in the beam path and is disposed downstream of the scannersystem 14 and serves for rotating a scanning plane defined by thescanning movement s′ and the optical transmission axis about the opticaltransmission axis, for example a K-mirror. In FIGS. 1 a and 1 b, thelaser beam L with the scanning plane rotated by the rotation element 12is designated by the reference sign Lr.

In one embodiment variant, the ophthalmological device 1 comprises afurther, optional scanner system 11 disposed upstream of the projectionoptical unit 10 and downstream of the scanner system 14. The scannersystem 11 is designed to scan the eye tissue with the pulsed laser beamL or the laser pulses along a processing line b, as is illustrated byway of example in the plan view in FIG. 4 a. A meandering processingline b is illustrated in the example in FIG. 4 a; the person skilled inthe art will understand that the processing line b, depending on theapplication and driving of the scanner system 11, can also assume otherline shapes, for example spiral, circular, or a freeform shape extendingover a part or all of the region B of the eye tissue that is to beprocessed. The scanner system 11 is embodied as a mechanical scannerthat moves the projection optical unit 10 over the entire processingregion B along the processing line b by means of one or a plurality ofmovement drivers, or the scanner system 11 is embodied in abeam-deflecting fashion, for example as a galvanoscanner, and comprisesone or two deflection mirrors—movable about respectively one or twoaxes—for deflecting the pulsed laser beam L or the laser pulses over theentire processing region B along the processing line b.

The scanner system 14 disposed upstream of the scanner system 11 has ascanning speed that is a multiple of the scanning speed of the scannersystem 11. Accordingly, the scanner system 14 can also be designated asa fast scan system that generates the deflected laser, beam Lfs, and thescanner system 11 can be designated as a slow scan system that generatesthe deflected laser beam Lss. The two scanner systems 11, are designedand coupled such that the scanning movement s′ running along thescanning line s is superimposed on the processing line b, as isillustrated schematically and by way of example in the x/y plan view inFIG. 4 a. As the scanning line s defines a cutting line in the case of asingle scanner system 14 having a single scanning axis, a cutting areais thus defined by the superimposition of the scanning line s onto theprocessing line b.

As is illustrated schematically in FIG. 1, the ophthalmological device 1furthermore comprises a tilting system 4 for tilting the scanning line sor the cutting area. As can be seen in FIGS. 1 d and 2 b, the tiltedscanning line s* is tilted by the tilting angle γ relative to thescanning line s in a plane running through the optical axis o of theprojection optical unit 10 and of the scanning line s. Accordingly, thetilting system 4 also enables a tilting of the cutting area defined bythe scanning line s and processing line b by the tilting angle γ, forexample—depending on the application and control—a tilting of the entirecutting area or of individual paths defined by the processing line b.

In the example in FIG. 4 a, the scanning movement s′ running along thescanning line s or the tilted scanning line s* is superimposed on themeandering processing line b and thus generates a cutting area extendedover the processing region B when moving over the entire processing lineb. FIGS. 4 b and 4 c show the cross-sectionalillustrations—corresponding to FIG. 4 a—of the cornea 22 applanated bymeans of the contact body 31 after moving over a path or four successivepaths of the processing line b with a scanning movement s′ along thetilted scanning line s*. The tilted scanning line s* of the exemplaryapplication illustrated in FIGS. 4 a, 4 b, 4 c enables the correction orremoval of residual errors in mutually adjacent processing paths whicharise when the optical axis o of the projection optical unit 10 is notoriented perpendicularly to the applanation area of the contact body 31.

The exemplary application in FIG. 5 shows, in the upper part, a planview of the cornea 22 and a schematically illustrated conic path cut 23made therein, the cross section of which is illustrated in the lowerpart of FIG. 5. The conic path cut 23 is produced by the superimpositionof a scanning movement s′ performed along a tilted scanning line s* ontoa circle-arc-shaped processing line b, wherein the tilted scanning lines* is oriented for example perpendicularly to the processing line b.

The exemplary application in FIG. 6 shows, in the upper part, a planview of the cornea 22 and two schematically illustratedcircle-arc-shaped vertical cuts 24 made therein, a cross section ofwhich is illustrated in the lower part of FIG. 6. The two vertical cuts24 are in each case produced by the superimposition of a scanningmovement s′ performed along a tilted scanning line s* onto acircle-arc-shaped processing line b, wherein the tilted scanning line s*is additionally oriented in the direction of the relevant processingline b.

The exemplary application in FIG. 7 shows, in the upper part, a planview of the cornea 22 and a plurality of schematically illustratedvertical cuts 25 made therein, which are oriented rectilinearly toward acenter point Z (vertex) of the cornea 22 and a cross section of which isillustrated in the lower part of FIG. 6. The vertical cuts 25 are ineach case produced by the superimposition of a scanning movement s′performed along a tilted scanning line s* onto a rectilinear processingline b oriented toward the center point Z (vertex) of the cornea 22,wherein the tilted scanning line s* is additionally oriented in eachcase in the direction of the relevant processing line b.

In order to control the tilting of the scanning line s or the cuttingarea, the tilting system 4 comprises a control module 40, which isdesigned to control components of the tilting system 4 in such a waythat the scanning line s (and thus, if appropriate, also the cuttingarea) is tilted by a predefined tilting angle γ in a plane runningthrough the optical axis o of the projection optical unit 10 and thescanning line s. The tilting angle γ is fixedly defined, for example, isinput via a user interface or is constantly changed by a controlfunction of the control module 40 during the processing of the eyetissue. The control module 40 comprises a programmable control device,for example one or a plurality of processors with program and datamemory and programmed software modules for controlling the processors.

Depending on the embodiment variant, the tilting system 4 comprisesdifferent components which are provided for tilting the scanning line sand are connected to the control module 40 for control purposes.

FIG. 1 a illustrates an ophthalmological device 1, in which the tiltingsystem 4 comprises one or a plurality of optical elements 13 which,disposed upstream of the projection optical unit 10, are arranged in thebeam path from the scanner system 14 to the projection optical unit 10and which are designed to generate in the beam path a divergence δ, δ₁,δ₂ of the laser beam L, said divergence being dependent on the scanningangle β, β₁, β₂ (see FIG. 2 b).

As is illustrated in FIG. 1 a, the optical element 13 is disposeddownstream of the scanner system 14 and varies the divergence δ, δ₁, δ₂of the laser beam L depending on the scanning angle β, β₁, β₂ of thelaser beam L deflected by the scanner system 14. The laser beam L withthe divergence δ, δ₁, δ₂ varied by the optical element 13 depending onthe scanning angle β, β₁, β₂ is designated by the reference sign Ldd inFIGS. 1 a and 2 b. In the embodiment variant with the optional rotationelement 12, the optical elements 13 or the optical element 13 are/isdisposed upstream of the rotation element 12 in the beam path.

As is illustrated in FIG. 2 a, the laser beam L in the absence of theoptical element 13 has in each case an unchanged, constant divergence δfor different scanning angles β, β₁, β₂. A divergence δ of approximatelyzero is often set. With the optical element 13 present, however, thelaser beam L has a different divergence δ₁, δ₂ for different scanningangles β, β₁, β₂, as illustrated in FIG. 2 b. As can be seen in FIG. 2b, the optical element 13 is designed such that it varies the divergenceδ, δ₁, δ₂ of the laser beam L depending on the scanning angle β, β₁, β₂such that the focus F, F* of the projected laser beam is displaceddepending on the scanning angle β, β₁, β₂ in the projection direction,thus resulting in a tilted scanning line s* which is tilted from theuntilted scanning line s by the tilting angle γ in the plane formed bythe optical axis o of the projection optical unit 10 and of the scanningline S. When the scanning line s is tilted, the eye tissue is scanned ina beam-deflecting manner along the tilted scanning line s* by thescanner system 14 with the pulsed laser beam L in a scanning movement s′performed over the scanning angle β, as is illustrated in FIG. 2 b. Inthis case, the focus F of the projected laser beam L* is moved by thescanning movement s′ along the tilted scanning line s*, for exampleproceeding from the position of the focus F in the case of a deflectionof the laser beam L with the scanning angle β₁ toward the position ofthe focus F* in the case of a deflection of the laser beam L with thescanning angle β₂.

Embodiments of the optical elements 13 or of the optical element 13comprise, for example, wedge plates, prisms, lenses, diffractive opticalelements and aspherical mirrors.

In an alternative embodiment variant, the optical element 13 is arrangeddirectly in the scanner system 14 and configured, for example, as adeflection mirror having a variable surface curvature.

In order to set the divergence δ, δ₁, δ₂ of the laser beam L dependingon the scanning angle β, β₁, β₂, the optical elements 13 or the opticalelement 13 can be introduced into the beam path or withdrawn from thebeam path. As an alternative or in addition, the optical elements 13 orthe optical element 13 can be set or adjusted for the purpose of settingthe divergence δ, δ₁, δ₂ of the laser beam L depending on the scanningangle β, β₁, β₂, for example by rotation of the optical elements 13about the optical axis o, by tilting of the optical elements 13 about anaxis of rotation, or by displacement of the optical elements 13 along atranslation axis tilted relative to the optical axis o.

In the embodiment variant with the optional scanner system 11, whichscans the eye tissue with the laser beam L or the laser pulses along aprocessing line b on which the scanning movement s′ of the scannersystem 14 disposed upstream is superimposed, the optical elements 13 aredesigned to generate the divergence δ, δ₁, δ₂ of the laser beam Ldepending on the scanning angle β, β₁, β₂ for a targeted tilting of acutting area defined by the scanning line s and the processing line b.

The control module 40 is designed to set the optical elements 13 or theoptical element 13 such that the divergence δ, δ₁, δ₂ of the laser beamL depending on the scanning angle β, β₁, β₂ brings about a tilting ofthe scanning line s or of the cutting area defined by the scanning lines and the processing line b by the predefined tilting angle γ. For thispurpose, the control module 40 comprises a control function which, fortilting angles γ that are predefined or constantly calculated anewduring the processing of the eye tissue, determines respectivelyassigned control values for setting the optical elements 13, for examplecontrol values for setting an angle of rotation of the optical elements13 about the optical axis o, a degree of tilting of the optical elements13 about an axis of rotation or a position of the optical elements 13 ona translation axis tilted relative to the optical axis o, therebydefining the relative position of the optical elements 13 in the beamcross section, or a surface curvature of the optical elements 13.

FIG. 1 b illustrates an ophthalmological device 1 in which the tiltingsystem 4 comprises a divergence modulator 15, which is disposed upstreamof the scanner system 14 and which is designed to dynamically vary thedivergence δ of the laser beam L.

FIG. 3 schematically illustrates an embodiment variant of the divergencemodulator 15 having two serially arranged optical lenses 151, 152, atleast one of which is displaceable for modulating the divergence δ ofthe laser beam L on an optical transmission axis w. For dynamicallymodulating the divergence δ of the laser beam L, the movable lens 151 iscoupled to a movement driver. As can be seen in the example in FIG. 3,in the case of a first basic position 151′ of the movable lens, thelaser beam L has a corresponding divergenceδ₁. In the case of adisplacement of the movable lens 151 on the transmission axis w, thedivergence of the laser beam L varies continuously and has a changeddivergence δ₂ in the case of the position 151″ displaced by theexcursion distance Δ. The laser beam L with the divergence δ, δ₁, δ₂modulated by the divergence modulator 15 is designated by the referencesign Ld in FIGS. 1 b, 2 b and 3.

In alternative embodiments, the divergence modulator 15 comprises aspatial light modulator for modulating the wavefront of the laser beamL, a surface light modulator for modulating the reflection angles at aplurality of points of a reflection surface over which the laser beam Lis guided, a refraction modulator for modulating the refractive index ofan optical element at a plurality of points in the cross section of thebeam path, and/or an amplitude modulator for amplitude modulation at aplurality of points in the cross section of the beam path, that is tosay in the beam profile, of the laser beam L.

The divergence modulator 15 is designed to modulate the divergence δ,δ₁, δ₂ of the laser beam L (during the scanning movement s′) with afrequency or speed of at least the same magnitude as that with which thescanner system 14 performs the scanning movement s′ over the scanningangle β. Moreover, the divergence modulator 15 is coupled to the scannersystem 14 such that the variation of the divergence δ, δ₁, δ₂ of thelaser beam L is synchronized with the scanning angle β, β₁, β₂ of thescanning movement s′. As is illustrated schematically in FIG. 2 b, thisresults in a divergence δ, δ₁, δ₂ of the laser beam L which varies withthe scanning angle β, β₁, β₂, i.e. is dependent on the scanning angle β,β₁, β₂.

The divergence modulator 15 can be set and controlled by the controlmodule 40 with regard to modulation frequency or modulation speed andmodulation depth or modulation intensity, e.g. the excursion distance Δin the embodiment according to FIG. 3. The modulation frequency of thedivergence modulator 15 is synchronized for example with the scanningspeed of the scanner system 14, e.g. a displacement over the excursiondistance Δ is carried out during a scanning movement s′ over thescanning angle β (e.g. from β₁ to β₂).

As has already been described above in connection with the opticalelement 13, in the case of a divergence δ, δ₁, δ₂ of the laser beam Lthat is varied depending on the scanning angle β, β₁, β₂, a displacementof the focus F, F* of the projected laser beam L*, said displacementbeing dependent on the scanning angle β, β₁, β₂, arises, as isillustrated by way of example in FIG. 2 b. In the case of correspondingsynchronization of the variation of the divergence δ, δ₁, δ₂ of thelaser beam L with the scanning angle β, β₁, β₂ of the scanning movements′, a tilting of the scanning line s results. The tilting angle γbetween the tilted scanning line s* and the untilted scanning line s inthe plane formed by the optical axis o of the projection optical unit 10and of the scanning line s can be adjusted by the modulation depth ormodulation intensity, e.g. by the excursion distance Δ.

If the divergence modulator 15 is designed to modulate the divergence δ,δ₁, δ₂ of the laser beam L with a greater frequency or speed than thescanner system 14 performs the scanning movement s′, this does not makeit possible to tilt the scanning line s merely by the tilting angle γ,but rather to deform the scanning line s in the plane formed by theoptical axis o of the projection optical unit 10 and of the untiltedscanning line s, wherein, in the case of a varying modulation speed, a“nonlinear tilting” and thus a deformation of the scanning line s in theprojection direction are also made possible.

In the embodiment variant with the optional scanner system 11, whichscans the eye tissue with the laser beam L or the laser pulses along aprocessing line b on which the scanning movement s′ of the upstreamscanner system 14 is superimposed, the divergence modulator 15 enables adivergence δ, δ₁, δ₂ of the laser beam L depending on the scanning angleβ, β₁, β₂ for a targeted tilting of the cutting area defined by thescanning line s and the processing line b. At a modulation speed of thedivergence modulator 15 which is higher than the scanning speed of thescanning system 14, the divergence modulator 15 enables a targeteddeformation of said cutting area.

The control module 40 is designed to set the divergence modulator 15such that the divergence δ, δ₁, δ₂ of the laser beam L depending on thescanning angle β, β₁, β₂ brings about a tilting of the scanning line sor of the cutting area defined by the scanning line s and the processingline b by the predefined tilting angle γ. For this purpose, the controlmodule 40 comprises a control function which, for tilting angles γ thatare predefined or constantly calculated anew during the processing ofthe eye tissue, determines respectively assigned control values forsetting the divergence modulator 15, in particular for setting themodulation depth or modulation intensity, e.g. the excursion distance Δ,and the modulation speed, wherein the synchronization between thescanner system 14 and the divergence modulator 15 is preferably effectedvia common synchronization lines or synchronization signals. For atargeted deformation of the cutting area defined by the scanning line sand the processing line b at a correspondingly high modulation speed ofthe divergence modulator 15, the control module 40 controls thedivergence modulator 15 with dynamically changing control values for amodulation depth or modulation intensity, e.g. the excursion distance Δ,and/or modulation speed varying during the scanning movement s′.

In an embodiment variant in accordance with FIG. 1 b, theophthalmological device 1 merely comprises one scanner system 14 or 11,for example a galvanoscanner system, which is disposed between thedivergence modulator 15 and the projection optical unit 10 and which isdesigned to scan the eye tissue two-dimensionally, that is to say bothin a first scanning direction x and in a second scanning direction yperpendicular thereto (see FIG. 4 a), in a processing fashion along ascanning line s or processing line b. The control module 40 is designedto control the scanner system 14 or 11 for the processing of the eyetissue along different scanning lines s or processing lines b whichhave, for example, a meandering, spiral, circular or freeform shape andextend over a part or all of the region B of the eye tissue that is tobe processed. The control module 40 is additionally designed to controlprocessing depth in the z-direction, which is perpendicular to the firstscanning direction x and second scanning direction y, by correspondingsetting of the divergence modulator 15. The processing depth in thez-direction can thus be modulated by corresponding driving of thedivergence modulator 15 by the control module 40 during the processingof the eye tissue in the scanning directions x, y along the scanningline s or processing line b. As a result, not only planar but alsocurved cutting areas are possible in the eye tissue, in particularcutting areas shaped in a targeted manner, for example parts of spheresurfaces, ellipsoid surfaces, one-dimensionally or two-dimensionallyundulatory shapes or other freeform areas, without the projectionoptical unit 10 or optical components thereof having to be moved forthis purpose. In this case, both the depth adjustment range in the eyetissue that is made possible by the variable setting of the modulationdepth or modulation intensity of the divergence modulator 15 in thez-direction, and the excursion range of the requisite excursion distanceΔ of the lens 151 are significantly smaller than the thickness of thecornea 22, of the lens or of other tissue parts of the eye.Consequently, in the eye tissue a modulation of the processing depth inthe z-direction is possible with a significantly higher frequency thanwould be possible by moving the large mass of the projection opticalunit 10 or optical components thereof.

FIG. 1 c illustrates an ophthalmological device 1 in which the tiltingsystem 4 is based on the projection optical unit 10, which is configuredsuch that it can be tilted about an axis of rotation q (or q′) runningperpendicularly to its optical axis o and to the scanning line s. As isindicated with the axis of rotation q′, the axis of rotation q′ need notrun directly through the optical axis o and the scanning line s; itsuffices if the axis of rotation q, q′ runs perpendicularly to a planedefined by the scanning line s and the optical axis o.

As is illustrated in FIG. 1 d, a tilting of the projection optical unit10 about the axis of rotation q, q′ with the rotation angle γ* bringsabout a tilting of the scanning line s by the tilting angle γ=γ*. In theexample in FIG. 1 d, the tilted scanning line s* in the plane defined bythe scanning line s and the optical axis of the projection optical unitis tilted relative to the untilted scanning line s by the same tiltingangle γ as the optical axis o of the projection optical unit 10 relativeto a normal n to the surface with respect to the contact body 31.However, the tilting angle γ and the rotation angle γ* can also bedifferent, if e.g. the object- and image-side refractive indices of theprojection optical unit 10 are different.

In the embodiment variant with the optional scanner system 11, whichscans the eye tissue with the laser beam L or the laser pulses along aprocessing line b on which the scanning movement s′ of the upstreamscanner system 14 is superimposed, the projection optical unit 10 thatcan be tilted about the axis of rotation q, q′ enables a correspondingtilting of the cutting area defined by the scanning line s and theprocessing line b.

For setting and fixing the tilting of the projection optical unit 10 andthe resulting tilting of the scanning line s or cutting area, theophthalmological device 1 in one embodiment variant comprises anadjusting device 16 coupled to the projection optical unit 10.

For the automated tilting of the projection optical unit 10, theophthalmological device 1 in a further embodiment variant comprises adrive 17 coupled to the projection optical unit 10. Moreover, thecontrol module 40 is connected to the drive 17 for the purpose ofcontrolling the tilting of the projection optical unit 10 and theresultant tilting of the scanning line s or of the cutting area inaccordance with a tilting angle γ that is predefined or is constantlycalculated anew during the processing of the eye tissue.

The invention claimed is:
 1. An ophthalmological device for processingeye tissue by means of a pulsed laser beam, comprising: a projectionoptical unit for the focused projection of the laser beam into the eyetissue, a scanner system disposed upstream of the projection opticalunit for the beam-deflecting scanning of the eye tissue with the laserbeam in a scanning movement performed over a scanning angle along ascanning line wherein at least one optical element is disposed upstreamof the projection optical unit, which optical element is configured togenerate a divergence of the laser beam, said divergence being dependenton the scanning angle.
 2. The ophthalmological device of claim 1,wherein the at least one optical element is designed to generate thedivergence—dependent on the scanning angle—of the laser beam for adisplacement of the focused projection in the projection direction, saiddisplacement being dependent on the scanning angle.
 3. Theophthalmological device of claim 1, wherein the at least one opticalelement is configured to generate the divergence—dependent on thescanning angle—of the laser beam for a targeted tilting of the scanningline.
 4. The ophthalmological device of claim 1, wherein the at leastone optical element is configured to generate the divergence—dependenton the scanning angle—of the laser beam for a tilting of the scanningline with a defined tilting angle in a plane defined by the scanningline and an optical axis of the projection optical unit.
 5. Theophthalmological device of claim 1, wherein the at least one opticalelement for setting the divergence—dependent on the scanning angle—ofthe laser beam can be introduced into the beam path and can be withdrawnfrom the beam path.
 6. The ophthalmological device of claim 1, whereinthe at least one optical element for setting the divergence—dependent onthe scanning angle—of the laser beam is adjustable in the beam path. 7.The ophthalmological device of claim 6, wherein the at least one opticalelement is adjustable by at least one from the following operations:rotation about an optical axis, rotation about an axis parallel to theoptical axis, tilting about an axis of rotation and displacement along atranslation axis tilted with respect to the optical axis.
 8. Theophthalmological device of claim 1, wherein the at least one opticalelement comprises at least one from the following list: wedge plate,prism, lens, diffractive optical element and aspherical mirror.
 9. Theophthalmological device of claim 1, further comprising a rotationelement arranged in the beam path for rotating a scanning plane definedby the scanning movement about an optical transmission axis, wherein theat least one optical element is disposed upstream of the rotationelement in the beam path.
 10. The ophthalmological device of claim 1,comprising a further, second scanner system disposed downstream of thescanner system and serving for scanning the eye tissue with the laserbeam along a processing line, wherein the scanning movement of theupstream first scanner system is superimposed on the processing line,and wherein the at least one optical element is configured to generatethe divergence—dependent on the scanning angle—of the laser beam for atargeted tilting of a cutting area defined by the scanning line and theprocessing line.
 11. The ophthalmological device of claim 1, wherein theat least one optical element is arranged in the beam path from thescanner system to the projection optical unit.
 12. The ophthalmologicaldevice of claim 1, wherein the at least one optical element is arrangedin the scanner system.
 13. The ophthalmological device of claim 1,further comprising a control module, which is configured to adjust theat least one optical element in such a way that with thedivergence—dependent on the scanning angle—of the laser beam thescanning line is tilted with a predefined tilting angle.
 14. Theophthalmological device of claim 13, wherein the control module isconfigured to adjust the at least one optical element in such a way thatwith the divergence—dependent on the scanning angle—of the laser beamthe scanning line is tilted with the predefined tilting angle in a planedefined by the scanning line and an optical axis of the projectionoptical unit.
 15. The ophthalmological device of claim 13, wherein thecontrol module is configured, during the processing of the eye tissue,to determine a changed tilting angle and to adjust the at least oneoptical element in such a way that the scanning line is tilted with thechanged tilting angle.